Ie. You could go into a dark room, imagine the moment you want to return to, clench your fists, close your eyes and you're there.
Would it be morally wrong to use this in relationship so you could always have that "perfect moment"?

I would use it to not get acquainted with certain people who, as it turns out are a bunch of childish, self-centered, gossipy, tactless, manipulative and narcissistic bunch of people that I've ever had the displeasure to know.